Were the visual and odor aspects hidden from the participants? If you put some monkeys in a blank white room to do some tasks and some others in a room with vi

Were the visual and odor aspects hidden from the participants? If you put some monkeys in a blank white room to do some tasks and some others in a room with visible Flora and the smell of Earth and plants, I suspect the lattre group would perfo better even with O2 an CO2 levels constant.